Mounting for x-ray intensifying screens



March 12, 1940. H, J, D|E1z 2,193,021

MOUNTING FOR X-RAY INTENSIFYING .SCREENS Filed Feb. 16, 1939 Patented Mar. 12, 1940 vPA'IENT OFFICE MOUNTING FOR X-RAY INTENSIFYING SCREENS Herbert J. Dietz, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a. corporation of 'New Jersey Application February 16, 1939, Serial No. 256,771

6 Claims.

The present invention relates to yX-ray cassettes, and more particularly to a new and novel arrangement lfor mounting an intensifying screen therein.

Such cassettes are usually made of a substantially rigid material, such as metaly and formed with a radioiucent front window through which the X-ray may pass to expose the sensitized nlm positioned within the cassette. In order to reduce the time required for exposing the sensitized film, such cassettes are usually provided with intensifying screens positioned on opposite sides of the film. These screens, as is well known, have the surfaces in contact with the film coated with a suitable material which iiuoresces when exposed to X-rays so as' to reduce i the time of exposure. In order to be most ef'- ective, it is highly essential that intimate contact be maintained between the uorescent surfaces oi the screens and the emulsion coatings of the film over the entire area of the latter.

Such intensifying screens are usually secured in position in the cassettes by means of a liquid adhesive, such as rubber cement, shellac, or by double-faced adhesive tape, none of which are entirely satisfactory. When rubber cement is used, a compound is formed which liberates peroxide, which in turn fogs the lm. In addition, small humps may be formed at the points of application of the cement, which humps tend to hold portions oi the screen out of intimate contact with the iilrn, the disadvantages of which are weli known to those in the art. It has also been found that when shellac is used to secure the screen, the shellac will dry out and shrink, and cause small depression areas in the screen at the points of the application of the shellac, thus preventing the required screen to nlm contact. Adhesive tape, due to the presence of cement in the adhesive, also fogs the nlm and is Vtherefore unsatisfactory. Furthermore, when the screens are thus adhesively secured, considerable difficulty is experienced in removing the screens to correct or adjust the felt pads, or other backing, which is positioned between the screen and the cassette, as is well known.V During such removal, the screens, which are vquite expensive, `are often damaged, the disadvantages of which are obvious. l

It is thus apparent that the present practice of adhesively securing the intensifying screen in position in the cassette is not entirely satisfactory. In order to overcome these diiculties, the present invention has as one of its objects the `provision of a new and novel arrangement by (Cl. Z-68) which the screen may be secured in position in the cassette without lthe use of adhesives of any type.

Another object of the invention is the provision of screen mounting or securing means which permits ready and easy removal of the screen without damaging the latter, yet maintains the screen in intimate contact with the lm during exposure.

Still another object of the invention is the provision of screen securing means which permits ready and easy adjustment or correction o? the flexible backing pad without in no way, damaging the latter. i

Yet another object of the invention is the provision of screen securing means which are simple and rugged in construction, inexpensive to manufacture, and extremely effective in use.

To these and other ends, the invention resides in certain improvements and combinations of parts all as will be hereinafter more fully described, the novel features being pointed out in the claims at the end of the specication.

In the drawing:

Fig. 1 is a perspective view of a cassette, with the back in open position, showing the preferred form of screen securing or mounting means;

Fig. 2 is a vertical sectional view through the cassette in closed position, showing the arrangement of the screw holding means illustrated in Fig. 1;

Fig. 3 is a vertical sectional view through the cassette illustrated in Fig. 2, showing a modied arrangement for detachably securing the intensifying screen to the cassette case;

' Fig. 4 isa perspective view of a corner of the nlm and one of the screens illustrated in Fig. 3, showing the method of recessing or countersink- -ing a corner of the back screen to position the head of screws of the screen securing members;

and

Fig. 5 is a View similar to Fig. i, showing still another way of securing the `screen in position in the cassette.

Similar reference numerals throughout the various views indicate the same parts.

The drawing shows an X-ray cassette formed to provide a case l l made of any suitable substantially rigid material impervious to X-rays, such for example as metal. The case is provided with a back l2 hingedly secured to the case il along one edge I3 to afford access to the interior of the cassette to permit insertion and/orremoval of a sensitized iilm I4. This lm is usually doublecoated with a sensitized emulsion and is positioned between a pair of intensifying screens I5 and I6 the lm contacting faces or surfaces I'I of which are coated with a suitable uorescent material, as is well known. Either or both screens I5 and I6 may be backed by a suitable flexible pad I8, such as felt, which is positioned betweenvthe screen and the case II, as shown in Figs. 2 and 3. The front ofthe case I I is provided with a radiolucent window I9 through which the X-rays may pass to expose the sensitized lm II.

In the preferred construction, as shown in Figs. 1 and 2, the back screen I5 is detachably or demountably secured to the hinged back II. To this end, the corners 24 of the screen I5 are'provided with openings 25 which register with similar openings 26 and 2l formed in the pad I8 and back I2 respectively, as shown in Fig. 2. Shanks 23 of bolts extend through these registering openings and have the outer ends 29 thereof threaded to receive nuts 30 by which the bolts may be drawn up into screen clamping or securing position as shown in Fig. 2. A locknut 3l is preferably positioned under each nut 36, as clearly shown in Fig. 2. The inner end of each bolt is upset to provide a head portion 32 arranged to overlie and engage the face II of the screen `I5 adjacent the opening 25.

It is apparent that when the nuts 3 are drawn up, the heads 32 of the bolts will engage and secure the screen I5 to the back II, as shown in Fig. l. It is also apparent that the screen I5 may be removed or detached from the back II merely by backing off the nuts 35 from the Shanks 28. As the screen I6 is on the bottom of the cassette when the latter is open, as shown in Fig. 1, it has not been found necessary to also detachably secure this screen to the cassette case. It is obvious, however, that the screen I6 may, if desired, be secured in the same manner as the screen I5.

The bolt heads 32 may be slotted at 33 so that the bolts may be tightened by turning the heads 32 and shanks 28. However, in order to prevent injury to the fluorescent surface I'I, it is preferred to hold the heads 32 and shanks 28 stationary and merely turn the nuts 36 to tighten the screen clamping bolts, as will be appreciated by those in the art.

As the heads 32 of the bolts project above the surface II of the screen I5, it is apparent, upon inspection of Fig. 2, that these heads will engage the corners of the opposite screen I 6 to hold the latter out of intimate contact with the lm Ill. In order that both surfaces I'I may properly contact the film, the corners 34 of the screen I 6 are cut away to afford recesses 35 which are arranged in registry with the heads and into which the heads may be positioned when I the bolt heads 32 are moved out of contact with the lm I4 and the latter may be removed and replaced by an unexposed film, after which the cassette may be closed to make another eX- posure, as is apparent. I I

In the embodiment shown in Figs. 3 and 4, the corners 39 of the back screen I5 are. skived or cut away through a portion of the screen thickness to provide shallow countersunk portions or recesses 4D in which the heads 32 of the bolts are positioned. As the heads 32 are quite thin, being about .02() inch in thickness, the countersunk portions 4I! are quite shallow so that the heads 32 may be broadly considered as engaging the surface I'I of the back screen I5. The head 32 of each screen securing bolt rests on the bottom 4I of the portion III), while the shank portion 42 extends through the registering openings 25 and 26 in the screen I5 and backing pad I8 respectively, and threadably engages an aligned opening 43 in the back II, as clearly shown in Fig. 3. It is obvious, of course, that the bolt shanks 112 may extend beyond the back I2 to receive nuts 36, as in Fig. 1. With the arrangement shown in Figs. 3 and 4 it is not necessary tocut away the corners of the opposite or front screen I6 as is the case in the embodiment shown in Figs. 1 and 2. For this reason the front screen I6 contacts the film III over the entire area thereof.

The modification shown in Fig. 5 is similar to thatl illustrated in Figs. 1 and 2 and differs therefrom only in that the bolts for securing the screen I5 are L-shaped so that the shanks 28 thereof do not pass through the screen itself. Parts corresponding to those in Figs. l and 2 are designated by the same numerals. 'Ihe inner ends of the bolts are formed with fiat radial extending portions or heads 56 which rest on and engage the surface I7 adjacent the corners thereof to detachably secure the screen I5 to the back I2. The registering corners 34 of the screen I6 are cut away, as described in connection with Figs. l and 2. It is obvious, of course, that the corners of the screen I5 may be skived to provide countersunk portions, as in Figs. 3 and 4. In which case, the bolt heads 46 would be positioned in the countersunk portions, and it would not then be necessary to cut the corners of the screen I6.

It is apparent from the above description that the present invention provides an arrangement' for detachably mounting an intensifying screen in an X-ray cassette without the use of adhesive, as in present practice. These screen securing members not only hold the screen in position, but permit ready and easy removal of the screen without in any way damaging the latter or the film backing pad. Such screen securing means eectively overcomes the difliculties inherent in the present method of adhesively securing the screen to the cassette.

While certain embodiments of the invention have been disclosed, it is to be understood that the inventive idea may be carried out 'in a number of other ways. This application is, therefore,

. not to be limited to the precise details described,

but is intended to cover all variations and modications thereof falling within the spirit of the invention or the scope of the appended claims.

I claim:

1. A cassette for holding a photographic film comprising a light tight case, an intensifying screen positioned within said case and having one face thereof formed with a fluorescent surface adapted to be positioned in intimate contact with said film, and screen retaining members in the form of bolts, each bolt having a shank portion detachably secured to said case and a head portion engaging said face to demountably secure said screen to said case.

2. A cassette for holding a photographic film through registering aperturesin said one screen comprising a light tight case, an intensifying screen positioned Within said case and having one face thereof formed With a fluorescent surface adapted to be positioned in intimate con tact with said film, meanshaving intermediate portions yexter'iding through registering openings in said screen and case, and end portions on said means engaging said case and said face to detachably secure said screen to said case.

3. A cassette for holding a photographic film comprising a light tight case, a pair of intensifying screens positioned onopposite sides of said film, each screen having one face thereof formed with a fluorescent surface adapted to be ar'- ranged in intimate contact with one face of said film, and screen holding members positioned adjacent the corners of one of said screens, each of v said members having a shank portion threadedly engaging said case and ahead portion engaging said one face of said one screen adjacent a cort ner thereof to removably secure said one screen to said case, the other of said screens having the corner thereof cut away to afford recess arranged to receive the head portions of said mem` bers. i n

4, A cassette for holding a ,photographic film ,comprising a light tight` case, 'a pair of` intensifying screens positioned on opposite sides of said film, each screen having one face thereof formed with a fluorescent surface adapted `to be arranged in intimate contact with one face of said film, screen holding members positionedadjacent the corners of one of said screens, each of said lmemhers having a shank portion arranged to extend and said case and detachably securedfto the lat*-y ter,4 and a head portion on each of said Shanks arranged to engage one face ofI said one screen face adapted to be positioned in intimate. contact with said film said screen having counterl one face thereof formed with a fluorescent surcuredvto `said case, and portions on said meme bers arranged to he positioned in said recess and latter to `said case. i

engage said vscreen to demountably secure the 6. A cassette for holding'a' photographic lm Y comprising a light tightv case, an intensifying screen positioned Within said, ,case and having one face thereof formed with a fluorescent sur-` face adapted to .be positioned in intimate ,con

tact with said'lm, said surface being formed with countersunk, corner portions, and screen securing member-comprising-bolts having Shanks projecting through and detachahly secured to said case and head portions engaging said corner portionsto demountably secure said screen ,i in position on said case.

iIERBrRTy J. METZ.

.sol

15 `sunk corner portions, members removably se-A v 

